Incendiary compositions

ABSTRACT

Self-igniting, gellike incendiary compositions are prepared by thickening aluminum alkyls and/or aluminum alkyl hydrides with an alkyl branched butadiene polymer. Additionally, the incendiary may contain diluents which are compatible with aluminum alkyls such as hydrocarbons, finely divided metals, and certain organometallic compounds. These incendiaries may be used in firebombs, fire rockets, flame throwers, aerial flares, and other military applications.

United States Patent [72] lnventor Davis M. Batson Baton Rouge, La. [21]Appl. No. 619,888 [22] Filed Feb. 24,1967 [45] Patented Jan. 11, 1972[73] Assignee Ethyl Corporation New York, N.Y.

[54] INCENDIARY COMPOSITIONS 4 Claims, No Drawings [52] U.S. Cl 149/87,149/109, 44/7 [51] Int. Cl C06b 15/00 [50] Field of Search 149/87, 109;44/7 [56] References Cited UNITED STATES PATENTS 2,765,329 10/1956Lindsey 149/87 X 3,084,181 4/1963 D'Alelio 149/109 X 3,280,088 10/1966DAlelio 149/109 X Primary Examiner-Carl D. Quarforth AssistantExaminerStephen J. Lechert, Jr. Attorney Donald L. Johnson ABSTRACT:Self-igniting, gellike incendiary compositions are prepared bythickening aluminum alkyls and/or aluminum alkyl hydrides with an alkylbranched butadiene polymer. Additionally, the incendiary may containdiluents which are compatible with aluminum alkyls such as hydrocarbons,finely divided metals, and certain organometallic compounds. Theseincendiaries may be used in firebombs, fire rockets, flame throwers,aerial flares, and other military applications.

INCENDIARY COMPOSITIONS BACKGROUND OF THE INVENTION This inventionrelates to incendiary compositions and to methods of dispensing them toproduce an effective conflagration.

Incendiary compositions such as contained in firebombs, fire rockets, orejected from flame throwers, now generally in use, are ignited by meansof a fuse, a spark, or some other external mechanism. The ignitionprocess may be commenced when the incendiary is propelled or releasedfrom the source or theigniti'on mechanism may be actuated when theprojectile strikes the target. While these ignition techniques haveachieved a degree of success, they are subject to malfunction and theincendiary composition may not ignite and, thus, is totally ineffective.

Current incendiary compositions consist mainly of gelled or thickenedgasoline. While this material is usually quite flammable, it must beindependently ignited and often does not burn completely. Upon strikingthe target, only that portion remaining in the area of ignition willburn. Because of its relatively high volatility, the unburned gasolinewill quickly vaporize and, thus, preclude any possibility of futureignition. Moreover, the burning of these compositions is not veryintense and may be extinguished or otherwise rendered ineffective forthe purpose intended.

Another shortcoming with current incendiary compositions, andparticularly those ejected from equipment such as a flame thrower, isthe extremely short range. Even when ejected under high pressure and,therefore, at high velocities, the in cendiary composition, ignited asit leaves the flame thrower, is completely burned within a relativelyshort range from the source. Thus, the use of this type equipment islimited to extremely short range applications.

SUMMARY OF THE INVENTION A self-igniting incendiary composition, havinga gellike consistency, is obtained by thickening from about 65 to about98 weight percent of an aluminum compound having the formula wherein Ris an alkyl group and x is an integer from one to three, with from about2 to about weight percent of cispolyisoprene gelling agent. Thecomposition may also contain from zero to about 20 weight percent of adiluent.

DESCRIPTION OF THE INVENTION The incendiary compositions of thisinvention are self-igniting incendiaries containing varying percentagesof aluminum compounds thickened with a polyisoprene. More specifically,the aluminum compounds contemplated are the alkyl and alkyl hydridealuminums, hereinafter referred to simply as aluminum alkyls. Thecompounds have the formula:

AIR,

11 where R is an alkyl group containing from one to four carbon atoms,and x is an integer ranging from one to three. In a preferredembodiment, R is a lower alkyl group containing up to three carbon atomsand x is equal to two or three. These materials are more reactive thanthe higher alkyls and, thus, assure maximum effectiveness. The mostpreferred embodiment comprises a composition wherein the aluminum alkylcomponent consists of from 90 to 100 percent triethylaluminum and fromzero to 10 percent diethylaluminum hydride. This composition ispreferred because it is of intermediate reactivity, volatility, andstability and is relatively economical to manufacture.

The compositions of this invention are incendiaries of extremely highreliability. They possess properties which produce a more intense andeffective conflagration than heretofore possible. Furthermore, theseincendiaries are selfigniting, burn with an intense flame, have lowvolatility, and are extremely difficult to extinguish. Afterdischarging, the incendiaries of this invention, as a rule, do notignite immediately but only after some delay, thereby increasing theeffective range of instrumentalities such as flame throwers. Uponignition, they provide an intense, widespread and effectiveconflagration.

The compounds which are useful in the incendiary compositions of thisinvention include trimethylaluminum, dimethylaluminum hydride,methylaluminum dihydride, triethylaluminum, diethylaluminum hydride,ethylaluminum dihydride, tripropylaluminum, dipropylaluminum hydride,propylaluminum dihydride, tributylaluminum, dibutylaluminum hydride,butylaluminum dihydride, triisobutylaluminum, diisobutylaluminumhydride, isobutylaluminum dihydride. The higher alkyl derivativesincluding the amyl and hexyl compounds and aromatic derivatives such asthe phenyl, tolyl, xylyl, etc. compounds of aluminum can also be used,especially as diluents and to impart certain characteristics to thealuminum alkyl mixture.

The polyisoprene employed in this invention may be prepared by any ofthe known methods such as fluid-bed, fixed-bed, and solutionpolymerization processes. The catalysts employed in any of the processesmentioned is not critical. Examples of the catalysts used in fluid-bedpolymerization processes are alfin catalysts which are complexes formedby a sodium salt of methyl-n-alkyl carbinol, e.g., sodium isopropoxide,and a sodium adduct with an olefin such as propylene, e.g., allylsodium;alkali metals such as lithium, sodium, potassium, cesium and rubidium;organolithium compounds including alkyl, allyl, aralkyl, and alkarylcompounds such as n-butyllithium, n-amyllithium, isoamyllithium, phenyl,tolyl, and benzyllithiums as well as polylithium hydrocarbons such ashexamethylenedilithium and 1,5- naphthalenedilithium; Ziegler-typecatalysts, especially those prepared from vanadium or titaniumtrichlorides, in conjunction with aluminum triethyl, as well ascatalysts prepared from vanadium oxychloride or chromylchloride andaluminum triethyl or zinc diethyl. Similar Ziegler catalysts can be alsoemployed in solution polymerization processes.

The molecular weight of the polymer is not critical. However, it shouldbe of such molecular weight and such viscosity that it would permit thepolymer to be at least partially soluble in lower alkylaluminumcompounds. Preferably, the polymer should be only partially soluble atambient temperature and considerably more soluble at elevatedtemperatures, especially around 100 C.

Although polyisoprene is preferable in this invention, other branchedchain butadienes may also be employed. Examples of such additionalpolymers are those obtained from monomers such as 3-ethyl-l,3-butadiene,3-propyl-l,3-butadiene, 3-butyl-l,3-butadiene,2,3-dimethyl-l,3-butadiene, 2,3-diethyl-l,3-butadiene,2,3'dibutyl-l,3-butadiene, and the like.

The most preferred polyisoprene employed in this invention iscis-polyisoprene which has a high cis-l,4 content. A specific example ofthis type of polyisoprene is Natsyn-ZOO. It is a beige colored solidpolyisoprene elastomer manufactured by a solution polymerization processemploying a stereospecific catalyst. The cis-l ,4-content of the polymeris approximately 95 percent, and the molecular configuration duplicatesthat of natural rubber. The polymer contains a nonstaining,nondiscoloring stabilizer. Although no molecular weight is given, theMooney viscosity ML4 at 212 F. is to 100.

This invention provides thickened or gelled incendiary compositions.Such compositions comprise from about 65 to about 98 weight percentaluminum alkyls, from about 2 to about 10 weight percent of a thickeningagent, and from 0 to about 25 weight percent of a diluent.

Another aspect of this invention provides a method of producing aconflagration which comprises dispersing a diluted or thickenedincendiary composition as described above in or over a target area.

The aluminum alkyls are ideally suited as incendiary materials, for uponcontact with air, they spontaneously ignite and burn with an intenseflame. Therefore, the igniting mechanism, which is required with priorart incendiaries, is eliminated. Concentrated aluminum alkyls also reactwith water to give a violent and sometimes explosive reaction. Thecompounds also react with other compounds containing active hydrogensuch as alcohols, amines, organic and inorganic acids, and to someextent, with materials such as paper and cloth. Therefore, theapplication of the incendiary compositions of this invention is notrestricted to an air media but can be used in a wide variety ofapplications with maximum reliability and effectiveness.

The thickened or gelled incendiary compositions generally adheretenaciously to the intended target. Also, by the addition of thethickening agent and, if desired, a diluent, the ignition delay periodof the aluminum alkyls may be altered so as to obtain the desiredduration. Moreover, in applications such as a flame thrower, a thickenedcomposition may be propelled over a long distance.

Depending upon the specific application, the incendiary compositions maybe in different forms. The consistency of the mixture may vary from amobile fluid to a highly thickened gel. The consistency is varied byincluding up to about percent of the thickener and, if desired, adiluent. Amounts of the diluents and thickeners in much greaterconcentration than the above limit impairs the ignition properties ofthe incendiary compositions.

The addition of diluents to the thickened aluminum alkyls serves avariety of purposes. By selection of the proper diluent, an incendiarycomposition may be obtained that has optimum properties with respect todensity, volatility, reactivity, ignition delay characteristics, etc.,and in many cases pro vides a more economical mixture. Broadly, anymaterial which is compatible and does not react with aluminum alkyls orthe thickener may be used as a diluent. It is preferable that thematerial to be used as a diluent is itself capable of combustion whenheated to its kindling temperature. The materials useable as diluentsinclude hydrocarbons, finely divided metals, and organometalliccompounds, preferably those not contain ing reactive functional groups,and not containing oxygen or reactive hydrogen. More specifically,petroleum derived hydrocarbons such as gasoline, kerosene, tar, asphalt,petroleum jelly, heavy lubricating oil, mineral oil, etc., are useable.Metals such as iron, magnesium, aluminum, zinc, boron, lithium, sodium,etc., in a finely divided state, or their organic compounds such asdiethylzinc, tributyl borine, may be used. Other organometalliccompounds may also be used, especially those containing a cyclomaticradical such as dicyclopentadienyl iron, methylcyclopentadienylmanganese tricarbonyl, dicyclopentadienyl manganese, etc. Other metalliccompounds may be included in the compositions, especially sodiumhydride, sodium aluminum hydride, sodium borohydride lithiumborohydride, or any of the sodium alkali metal hydrides, aluminumhydrides, or borohydrides. These normally solid compounds are partiallysoluble in the aluminum alkyls. The higher alkyl and aromatic compoundsof aluminum such as tripentylaluminum, trihexylaluminum,triphenylaluminum, etc., may also be included as diluents. Thesematerials are much less reactive than the lower alkyls and, thus, may beemployed to obtain a less reactive, more controllable incendiarycomposition.

The compositions of this invention are useable in a wide number ofmilitary applications. This invention provides tailormade" thickenedaluminum alkyls which are ideal for military incendiary use,specifically for antipersonnel or antimaterial applications. Thecompositions may also be used in fire bombs, fire rockets, in the formof frangible capsules or spheres propelled from devices such as acompressed gas gun or mortar which could launch a package of suchcapsules. Aluminum alkyl compositions are also ideally suited as flamethrower fuels. The compositions of this invention are self-igniting,producing a higher flame temperature than normally used materials suchas gelled gasoline and, in addition, cause both chemical and thermalinjuries to personnel. These compositions are also amenable tononmilitary applications such as flares either of the stationary type ordischarged from a hand pistol as aerial flares, etc.

An example of the incendiary bomb provided by this invention comprises asheet-steel shell having a ballistic configuration tapering down to aforward nose section which ,is constructed of heavy steel to facilitatepenetration into the intended target. The rear portion of the shellterminates in a tail assembly which includes an opening through whichthe shell is filled with the incendiary composition, and fins tostabilize the flight of the bomb and, thus, improve accuracy.Appropriate means such as a threaded plug are used to seal the openingafter filling. The bomb may be jettisoned from an aircraft singly or itmay be in a cluster from which individual bombs are released during thedescent. The above-described incendiary bomb is designed to fracture dueto its own momentum when it strikes the target, thereby releasing itscontent. Alternatively, the bomb may be equipped with any of thewellknown types of bursting charges for fragmenting the bomb shell andthereby forcefully expelling the incendiary compositions. A fusedesigned to function instantaneously upon impact or with a delayedaction is incorporated into the nose section to ignite a small charge ofexplosive material such as gun powder also contained therein. Theigniting mechanism may also be designed to fire while the bomb is inflight prior to striking target.

Many benefits accrue from the use of the incendiary compositions of thisinvention which were heretofore not obtainable. One important advantageis that the compositions are selfigniting when exposed to air.Accordingly, the independent ignition mechanism of current incendiariesis obviated, thereby precluding any failure of the ignition mechanism.

Another important advantage of this invention is that upon exposure toair, there is a certain delay period before self-ignition takes place.The ignition delay period varies with different aluminum alkylcompounds. For example, the ignition delay period for trimethylaluminumis much shorter than for a higher alkyl such as tributylaluminum.Moreover, the ignition delay period may be altered somewhat by alteringthe amounts of a polyisoprene thickening agent and of the diluent. Thus,a tailormade composition is available with various ignition delaysperiods. In this manner, the effective range of instrumentalities suchas flame throwers can be increased, and only a part of the fuel will beburned before reaching the intended target.

Another advantage in using the incendiaries of this invention is thatthey are less volatile then currently used materials for this purpose.The aluminum alkyls will not evaporate as readily as gasoline and, thus,the material will burn on the surface of the target, thereby providingmaximum effectiveness. The aluminum alkyls burn vigorously with anextremely hot flame and are, therefore, much more difficult toextinguish than conventional incendiaries. These incendiaries also burnwith a cleaner flame, with a minimum of smoke, thereby making itdifficult to locate and extinguish the flame.

The following examples illustrate the methods of preparing thecompositions of this invention. All parts are by weight unless otherwisespecified.

EXAMPLE 1 To a vessel placed in a nitrogen atmosphere were added lOOparts of triethylaluminum and 6 parts of cis-polyisoprene which wasfirst cut in approximately Az-inch cube-pieces. After heating themixture to about C., the contents were thoroughly mixed. The resultingincendiary composition had a consistency of medium thick gum and ignitedimmediately upon exposure to air.

A l-milliliter sample of the above composition was burned on an asbestosboard. A chromel-alumel thermocouple was inserted in the burning mass inthe various parts of the flame. The maximum flame temperature was foundto be l,330 F.

Similar compositions are obtained when in the above example, a mixtureof triethylaluminum and diethylaluminum hydride is employed in place oftriethylaluminum.

EXAMPLE 2 Following the procedure of example 1, 9 parts ofcispolyisoprene was mixed with 100 parts of triethylaluminum. Anincendiary having the consistency of a uniform heavy gum was obtained.Upon exposure to air, the composition exhibited delayed ignition.

About 20 weight percent of mineral oil is added to the abovecomposition. The resulting incendiary has a somewhat lighterconsistency.

A substantially similar composition is obtained when 10 parts ofcis-polyisoprene is employed.

EXAMPLE 3 Following the procedure of example 1, two parts ofcispolyisoprene was mixed with 100 parts of triethylaluminum. Theresulting incendiary had a consistency of light slush.

To the composition obtained in example 3 is added about weight percentof a diluent such as powdered iron, sodium, and aluminum. The resultingincendiary has a vapor pressure lower than the incendiary without adiluent.

In addition to the above specific embodiments, many other applicationsof the compositions of this invention and articles of manufacture willbe obvious to those skilled in the art. Besides other miscellaneousapplications such as booby traps and clandestine devices, thecompositions may be used in land mines, or rocket projectiles, and firestarters in general. These incendiary compositions may also be used fornonmilitary purposes as, for example, in fire bombs or aerial sprayingto start backfires" in fighting forest fires.

The aluminum alkyls are well known compounds. Methods for theirpreparation can be found in any standard texts including OrganometallicCompounds," by G. E. Coates, l960, John Wiley and Sons, Inc., New York,N. Y.; "Organic I Chemistry by P. Karrer, 1950, Elsiveier PublishingCompany, New York, N. Y., etc.

Having fully defined the novel incendiary compositions of this inventionand the methods of using them, it is desired that this invention belimited only within the lawful scope of the appended claims.

lclaim:

l. A thickened incendiary composition having a gellike consistencyconsisting essentially of from about 65 to about 98 weight percent of analuminum compound having the formula

2. The composition of claim 1 wherein said aluminum compound istriethylaluminum.
 3. The composition of claim 1 wherein said aluminumcompound is a mixture of triethylaluminum and diethylaluminum hydride.4. The composition of claim 1 consisting essentially of 94 weightpercent of triethylaluminum and 6 weight percent of cis-polyisoprene.